1. Field of the Invention
This invention relates generally to the joining of rigid couplings to elastomeric tubular structures for use with inflatable packers and fiber reinforced elastomeric hose or tubing and, more particularly, to couplings designed to interact with fiber reinforcements to become integral members of inflatable packer, hose and tubing assemblies. More specifically, the invention relates to improved coupling designs connecting with enhanced load capability for these assemblies to other such assemblies or other structures with which these assemblies communicate.
2. Description of the Prior Art
An inflatable packer is a down-hole tool which is inflatable with fluid or some other mechanism to seal off an annular space in a well bore. Inflatable packers generally include a tubular elastomeric structure or bladder that is inflated to expand and engage the inner surface of a well bore. A coupling is typically provided on at least one end of the bladder to connect the packer to a mandrel, other packers, or to a well string. Because inflatable packers operate under great pressure, both from the well environment and from the internal pressure necessary to inflate the elastomeric tubular structure to seal the well bore, the elastomeric tubular structure must preferably be reinforced. One such form of reinforcement includes the use of integral fibers, and the attachment of such a fiber reinforced structure to the coupling must be very strong. Integral fibers include, but are not limited to, random fiber impregnations, strands, and cords.
Some hose and tubing assemblies are likewise operated under great external and internal loads and pressures. These hose and tubing assemblies generally include an elastomeric tubular structure reinforced with integral fibers, and a coupling on at least one end to connect the assemblies to other hose or tubing assemblies and other structures with which the assemblies are adapted to function.
The prior art approaches for joining couplings to the fiber reinforced tubular structures of inflatable packer, hose and tubing assemblies, have included use of epoxies or numerous variations of applying a clamping pressure across the inner and outer surfaces of the tubular structures, or directly to the integral reinforcing fibers within the structures.
In order for inflatable packer, hose, and tubing assemblies to function properly, the junction of the couplings and tubular elastomeric structures must effectively seal. Prior art inflatable packer, hose, and tubing assemblies have upper pressure and load limits, above which the junction of the coupling and elastomeric tubular structure tends to fail. This is because the retentive force which the coupling can exert at the junction is exceeded, at which the junction loses its seal, and the elastomeric tubular structure separates from the coupling. The retentive force which the coupling can exert, where clamping is used, is limited to the friction generated across the surfaces of abutting tubular structures or the surfaces of the reinforcing fibers, as appropriate.
Consequently, there is still a need for a coupling design or structure which provides high retentive force and can withstand high pressures and internal loads without rupture of its seal or separation from the coupling.